Synthesis, Spectroscopy and Electrochemistry of Cobalt(III) Schiff Base Complexes

Thermodynamic Study of Cobalt(III) Schiff Base Complexes in Mixed EtOH/H2O

The [Co(Chel)(PBu3)]ClO4.H2O(Chel = dsp, mdsp and ndsp, where dsp = N,N′-disalicylidene-1,2-phenylene diamine, mdsp = 4-methyl-N,N′-disalicylidene-1,2-phenylene diamine and ndsp = 4-nitro-N,N′-disalicylidene-1,2-phenylene diamine), were synthesised and characterised. The equilibrium constants and the thermodynamic parameters of these complexes as acceptors with PBu3, were measured spectrophotometrically for 1: 1 adduct formation in various mixed EtOH/H2O and constant ionic strength (I = 0.1M NaClO4) and at various temperatures T = 288–308 K. The trend of the reactivity of five coordinate Co(III) Schiff base complexes toward PBu3 donor according to the Schiff base ligand is mdsp > dsp > ndsp. The trend of the reactivity of a given Co(III) Schiff base complexes towards PBu3 donor according to the water/ethanol mole fractions is 0.12 > 0.36 > 0.52 > 0.64.

Spectroscopy and Electrochemistry of Cobalt(Iii) Salophen Complexes

Novel Co(III) complexes with general formula, [Co(chel)(PBu3)]ClO4.H2O, where chel = 5-Brsalophen, 5-NO2salophen, 5-MeOsalophen and 4-MeOsalophen, were synthesised and characterised. The spectroscopic and electrochemical properties of these complexes and [Co(salophen)(PR3)]ClO4.H2O (R = PBu3 and PPh3) complexes were investigated.

Immobilization of cobalt(III) Schiff base complexes onto Montmorillonite-K10: Synthesis, experimental and theoretical structural determination

The [Co(naphophen)(PPh3)(OH2)]ClO4 and [Co(naphophen)(PBu3)(OH2)]BF4 (where naphophen=bis(naphthaldehyde)1,2-phenylenediimine) complexes were synthesized and chracterized by FT-IR, UV-Vis, (1)H NMR, (13)C NMR spectroscopy and elemental analysis techniques. The coordination geometry of the synthesized complexes were determined by X-ray crystallography. Cobalt (III) complexes have six-coordinated pseudo-octahedral geometry in which the O(1), O(2), N(1) and N(2) atoms of the Schiff base forms the equatorial plane. These complexes showed a dimeric structure via hydrogen bonding between the phenolate oxygen and the hydrogens of the coordinated H2O molecule. The theoretical calculations were also performed to optimize the structure of the complexes in the gas phase to confirm the structures proposed by X-ray crystallography. In addition, UV-Visible and IR spectra of complexes were calculated and compared with the corresponding experimental spectra to complete the experimental structural identification. The synthesized complexes were incorporated onto the Montmorillonite-K10 nanoclay via simple ion-exchange reaction. The structure and morphology of the obtained nanohybrids were identified by FT-IR, XRD, TGA/DTA, SEM and TEM techniques. Based on the XRD results of the new nanohybrid materials, the Schiff base complexes were intercalated in the interlayer spaces of clay. SEM and TEM micrographs of the clay/complex shows that the resulting hybrid nanomaterials has layer structures.

Novel nanohybrids of cobalt(III) Schiff base complexes and clay: synthesis and structural determinations

The [Co(Me(2)Salen)(PBu(3))(OH(2))]BF4 and [Co(Me(2)Salen)(PPh(3))(Solv)]BF(4), complexes were synthesized and characterized by FT-IR, UV-Vis, (1)H NMR spectroscopy and elemental analysis techniques. The coordination geometry of [Co(Me(2)Salen)(PPh(3))(H(2)O)]BF(4) was determined by X-ray crystallography. It has been found that the complex is containing [Co(Me(2)Salen)(PPh(3))(H(2)O)]BF(4) and [Co(Me(2)Salen)(PPh(3))(EtOH)]BF(4) hexacoordinate species in the solid state. Cobalt atom exhibits a distorted octahedral geometry and the Me(2)Salen ligand has the N2O2 coordinated environment in the equatorial plane. The [Co(Me(2)Salen)(PPh(3))(H(2)O)]BF(4) complex shows a dimeric structure via hydrogen bonding between the phenolate oxygen and hydrogens of coordinated H2O molecule. These complexes were incorporated into Montmorillonite-K10 nanoclay. The modified clays were identified by FT-IR, XRD, EDX, TGA/DTA, SEM and TEM techniques. According to the XRD results of the new nanohybrid materials, the Schiff base complexes are intercalated in the interlayer spaces of the clay. SEM and TEM micrographs show that the resulting hybrid nanomaterials have layer structures. Also, TGA/DTG results show that the intercalation reaction was taken place successfully.

Synthesis, spectroscopy, electrochemistry and thermal study of vanadyl tridentate Schiff base complexes

The VO(IV) complexes of tridentate ONO Schiff ligands were synthesised and characterized by IR, UV-vis and elemental analysis. The electrochemical properties of the vanadyl complexes were investigated by cyclic voltammetry. A good correlation was observed between the oxidation potentials and the electron withdrawing character of the substituents on the Schiff base ligands, showing the following trend: MeO<H<Br<NO(2) and H<Cl. The thermogravimetry (TG) and differential thermoanalysis (DTA) of the VO(IV) complexes were carried out in the range of 20-700°C. The VOL(1)(OH(2)) decomposed in two steps whereas the remaining six complexes decomposed in three steps. The thermal decomposition of these complexes is closely related to the nature of the Schiff base ligands and proceeds via first order kinetics.

Synthesis, spectroscopy, electrochemistry and thermal study of Ni(II) and Cu(II) unsymmetrical N2O2 Schiff base complexes

The new tetradentate unsymmetrical N(2)O(2) Schiff base ligands, Ni(II) and Cu(II) complexes were synthesised and chracterized by IR, UV-vis, (1)H NMR and elemental analysis. The electrochemical properties of the Ni(II) complexes were investigated. The thermogravimetry of the Ni(II) and Cu(II) complexes were carried out in the range of 20-700 degrees C. Decomposition of synthesised complexes is related to the Schiff base characteristics.